This invention relates to a thin reinforced nonwoven fabric for fire blocking an article, articles containing such fabrics, and methods for making the fabrics and fire blocking the articles. When exposed to heat or flame, the fabric is capable of increasing its thickness by at least three times. The fabric comprises an open mesh scrim having a having crimped, heat-resistant organic fibers compressed thereon and held in a compressed state by a thermoplastic binder. When subjected to high heat or flame, the binder in the structure softens and flows, releasing the restrained crimped fibers and allowing the thickness of the fabric to increase dramatically.